Numerous devices have been utilized in the art of breaking up rock. Most such devices are quite large, and are used in mining, quarries and excavation endeavors. These devices and methods are typically for large-scale efforts resulting in massive explosions, and the destruction or generation of large areas of rock. Few devices exist for specialized small scale breaking efforts; however, these devices tend to be larger than the present device and utilize far more explosive forces.
For example, U.S. Pat. No. 5,789,694 ('694) shows a tool and method for breaking up rock. The tool of '694 has a barrel, a breech body for receiving a gas discharge cartridge loaded with gas producing propellant and a firing-handle mechanism (a firing pin) for firing the cartridge. The method involves drilling a hole in rock, filling the hole with water, passing the barrel down the hole, and firing the cartridge. The cartridge used is similar to a shotgun cartridge and has a rim-fire percussion cap, which complements the firing pin. The device of '694 further utilizes a trigger assembly attached to a lanyard for remote triggering of the firing pin. In operation, the barrel is inserted into a water-filled hole while the cartridge, which is engaged at the top of the barrel opposite the bottom of the hole, is detonated by the firing pin thereby producing rapid gas expansion into the water generating shock waves throughout the water and fracturing of the rock. The triggering device is cocked before use, and the lanyard is pulled to fire the device from a remote location. The device additionally uses a blast shield.
The explosive gas cartridge of the '694 invention is placed in the middle of the device at the top of the barrel. The barrel of the '694 patent is used as a pipe for channeling the force of the detonated gas chamber into the bottom of the borehole. The device of '694 requires a blast shield indicating the great force released thereby. A smaller device, which has a smaller explosion, is desired so that the device may be used in circumstances not conducive to most explosions.
Many related art devices involve methods that require drilling boreholes and generating a rapid increase in the concentration of pressure in the bottom of a borehole either by explosions, or a sudden increase in fluid pressure, to facilitate and propagate fracturing of the rock. Many of these inventions are designed to excavate rocks or dig tunnels, and include various boom-supported devices. All of these devices use impact and expansive gas in order to break apart rock or other hard material. These devices are quite large and produce substantial explosions/gas expansions, and are otherwise unsuitable for the purposes of the present invention. The majority of the related art uses large-scale devices, which are disposed on boom arms.
Methods of breaking up rock which couple explosive (or rapid gas expansion) and mechanical impact breaking to excavate rock and dig tunnels are well known. U.S. Pat. No. 5,803,550 ('550) discloses a method for breaking rock using small-charge blasting techniques followed by a mechanical impact breaker. In the small-charge blasting technique, a gas is released into the bottom of a sealed hole. The gas pressure rises rapidly in the hole until the gas pressure causes the hard material to fracture followed by an impact breaker to complete the fracturing of the rock and to remove the fractured material. The '550 device involves a large mobile undercarrier having a boom assembly with a mechanical impact breaker and a small charge blasting apparatus attached thereto. It is desirable to have a very small charge blasting technique that is effective without using an impact breaker to increase the fracture of the rock generated by the detonation of the load.
Similarly, U.S. Pat. No. 5,308,149 ('149) uses a controlled-fracturing process accompanied by pressurizing the bottom of a drill hole in such a way as to initiate and propagate a controlled fracture. The process of '149 uses a large apparatus to operate.
U.S. Pat. No. 6,145,933 ('933) describes a method for removing hard rock by a combination of impact hammers and small charge blasting. The method of '933 uses small-charged blasting techniques followed by a mechanical impact breaker. In the small-charge blasting technique of the '933 patent, a gas is released into the bottom of a sealed hole located at a free surface of the rock. The gas pressure rises rapidly in the hole until the gas pressure causes the rock to fracture. A blasting agent may be used to cause initial subsurface fractures. An impact breaker is then used to complete fracturing and removal of the material. The devices utilized in the invention of '933 are large scale and are held into position by boom arms.
It is known in the art to seal or block the bore hole to increase the pressure at the bottom of the hole without using additional impact apparatuses. U.S. Pat. No. 6,148,730 describes a method and apparatus for controlled small-charge blasting by pressurization of the bottom of a drill hole. The invention therein involves drilling a hole in rock, inserting a cartridge containing an explosive apparatus, bracing the cartridge with a massive stemming bar in the drilled hole, and detonating the explosive thereby generating fractures in the rock. Likewise, U.S. Pat. No. 6,035,784 discloses a method and apparatus for controlled small-charge blasting of hard rock explosive pressurization of the bottom of a drill hole which uses a cartridge containing an explosive charge inserted into the bottom of a drilled hole wherein the cartridge is held in place by a massive stemming bar. The stemming bar also serves to partially block the hole increasing the pressure of the explosion.
U.S. Pat. No. 5,765,923 teaches a cartridge for generating high-pressure gases in a drilled hole. The cartridge includes a base member, a body member, a propellant, and a device for sealing a surface of the cartridge to the surface of a hole in the material. Upon ignition of the propellant, gas pressure rapidly rises in the hole due to the sealing device. The gas pressure causes the material to form a penetrating cone fracture. The cartridge is placed in a hole by a boom suspended from large-scale equipment. In operation, the cartridge is first loaded into a combustion chamber and a gas injector barrel is placed into the drill hole. A firing pin is actuated thereby triggering the primer, which in turn ignites the igniter power, which in turn ignites the propellant. As the propellant burns, pressure is built up within the cartridge. At a desired psi (pounds per square inch), the cartridge body ruptures releasing the generated gas into the combustion chamber and the barrel.
Many related art devices and methods involve apparatuses that insert explosives into a hole using a boom, which explosives may then be detonated remotely. Additionally, the boom arm may serve to partially seal the hole. U.S. Pat. No. 3,721,471 shows a drill-and-blast module which is disposed on the end of a boom for insertion in a hole and detonation thereof. U.S. Pat. No. 5,098,163 ('163) discloses a controlled fracture method for breaking hard compact rock which involves a boom supported apparatus that inserts an explosive, or a propellant charge, in a pre-drilled hole. The '163 apparatus may utilize a barrel to insert the explosives, and the hole may be sealed behind the explosive in an effort to control the explosion.
Furthermore, it is well known to use devices and methods, which increase fluid pressure by means other than explosive or rapid gas expansion, to break apart the rock. U.S. Pat. No. 4,669,783 teaches a process and apparatus for fragmenting rock using an explosion-free pulse of water directed into a borehole resulting in high-pressure shock waves that fractures the rock. U.S. Pat. No. 6,375,271 describes a controlled foam injection system for fragmentation of hard compact rock whereby a high pressure foam is inserted into a drill hole by a barrel, which seals the hole and is disposed at the end of a boom attached to heavy equipment.
Alternative detonation techniques and hybrid methodologies are also known. U.S. Pat. No. 2,058,099 describes a blasting cartridge that is inserted into a drill hole. High water pressure is exerted on the cartridge through a pipe resulting in a sudden explosive release of pressure increasing substance from the cartridge. U.S. Pat. No. 5,803,551 ('551) discloses a method, apparatus and cartridge, which are disposed on a boom truck, for non-explosive rock fragmentation. The '551 method involves first drilling a hole into a rock, positioning a charging system having a propellant cartridge inserted therein, which cartridge has a propellant and means for igniting the propellant, and forcing the propellant cartridge through the charging system and into the hole to ignite the propellant.
U.S. Pat. No. 6,318,272 teaches a method of breaking rock, which includes drilling a hole in the rock by a drilling machine having an articulated boom and a drilling tool at the end of the boom. After removing the drilling tool, a rock breaking charge is charged into the hole, which charge includes a propellant, a fuse head, and a tamping medium contained in a casing. The tamping medium is discharged into the hole and allowed to set around and rearward of the propellant. The driving mechanism is removed and the propellant is actuated from a remote position via electrical charge or the like.
U.S. Pat. No. 4,508,035 involves an explosive charging apparatus for rock drilling which charges a controlled amount of explosives sequentially to bores drilled in a rock surface and includes an explosive charging pipe, a boom mechanism carrying the explosive charging pipe, boom actuators, a control circuit and an explosive charging pipe. U.S. Pat. No. 5,611,605 describes a method, apparatus and cartridge for non-explosive rock fragmentation which involves drilling a hole into a rock, and inserting a propellant cartridge into a charging housing with a means for igniting the propellant, and forcing the propellant cartridge through a charging hose and into the hole to ignite the propellant. The apparatus and cartridge of '605 are inserted using a boom device.
It is known to use pressurized fluids in a hole to break rocks. U.S. Pat. No. 6,339,992 ('992) shows a small charge blasting apparatus including an apparatus for sealing pressurized fluids in holes. The invention therein provides a relief volume for a pressurized working fluid in the bore of a barrel that is inserted into a hole in the material to be broken. The invention seals the fluid into the hole while a gas-generator generates greater pressure. The requirement of a separate apparatus for sealing pressurized fluids into bore holes is inconvenient especially in any emergency rescue operations where the least amount of equipment, especially bulky equipment, in most desirable.
Numerous diverse methods and apparatuses have been developed to aid in breaking rock and other hard surfaces. U.S. Pat. No. 5,573,307 ('307) describes a method and apparatus for blasting hard rock using a highly insensitive energetic material ignited with a moderately high-energy electrical discharge causing the fracturing and break up of hard rock. The blasting apparatus of '307 has a reusable blasting probe which includes a high voltage electrode and a ground return electrode separated by an insulating tube. The two electrodes of the blasting probe are in electrical contact with a metal powder and oxidizer mixture that will generate an exothermic reaction upon generation of an electric current therebetween creating a gas expansion to fracture the rock.
U.S. Pat. No. 2,587,243 ('243) describes a cutting apparatus, which produces a very high velocity gaseous penetrating jet for cutting materials or objects using a chemical charge. No borehole is drilled prior to the use of the '243 apparatus. U.S. Pat. No. 3,208,381 shows a device for loading bore holes with explosives in bar-shaped or tubular packages, which device is a generally tubular sleeve constructed of resilient material to receive one end of an explosive package.
A variety of cartridges are used in the related art. Cone-shaped blasting cartridges or plugs are designed to contain or control the explosion in a drilled/bore hole. U.S. Pat. No. 5,705,768 shows a shaped charge to be placed into a bore hole, which shaped charge includes an elongate housing having a concave recess in an upper end, an explosive located within the housing and below the recess, and a detonator positioned beneath the recess and explosive.
Similarly, U.S. Pat. No. 2,296,504 ('504) teaches a blasting plug designed to control the level of explosion resulting from the detonation of dynamite, and prevent an uncontrolled explosion and resultant fire hazard. The method of using the device of '504 involves inserting the device in a borehole and detonating the device remotely. U.S. Pat. No. 5,900,578 describes a method of breaking slabs that involves drilling bore holes along a desired break line, inserting a detonating cord therein, filling the bore holes with a shock transmitting/moderating composition, and detonating the detonation cord.
U.S. Pat. No. 1,585,664 ('664) shows a method and apparatus for breaking rock which utilizes projectiles (similar to bullets) and a forcible ejection means attached to a boom. The projectiles are fired at the surface of the rock. The '664 invention demonstrates that the use of bullet-like explosives is known in the art. U.S. Pat. No. 5,069,130 describes a propellant igniter. U.S. Pat. No. 4,900,092 discloses a barrel for a rock breaking tool and method for breaking rock which involves drilling a hole in rock, filling the hole with water, inserting a short barrel of a rock breaking tool into the hole entrance, covering the tool with a recoil restraining mat, and discharging a cartridge down the barrel.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Specifically, these devices lack the simplicity and portability desired for truly small-scale rock breaking, and especially, for rock breaking that must not generate an explosion of any significant force.